Prototype Bluetooth Low Energy Preemption Proximity Alert System

Emergency response services play a vital role in saving lives and minimizing property damage when major events or incidents occur, and it is critical for emergency vehicles (EVs) to travel to their destinations while maximizing the timeliness and safety of their trip. However, traffic safety and efficiency are a concern for both EVs and civilian vehicles as EVs are in-route to calls, especially at intersections where conflicting vehicle paths are a risk. To improve safety and efficiency, the existing EV preemption systems allow an EV to request signal preemption (i.e., a green phase to be granted for the approach with the EV) at signalized intersections. The EV turns on the emergency sirens and strobe lights to alert nearby vehicles of its arrival. However, there is no alternative way of warning nearby vehicles when the drivers cannot be alerted properly by the sirens and lights. The recently developed mobile proximity warning system using Bluetooth low energy (BLE) technology may provide a way to broadcast signal preemption status inside vehicles near the intersection. The basic concept is that (1) a microprocessor in the traffic signal cabinet detects the approaching EV; (2) the microprocessor sends out a Bluetooth beacon broadcast to a beacon-aware software application on a mobile device, such as a smartphone carried inside the vehicles; and (3) the application broadcasts the alert message based on an active signal preemption or another predefined event. The beacon broadcast can alert nearby vehicles to the EV presence. This document provides a system overview of the proposed prototype BLE proximity alert system for EV preemption at signalized intersections. It provides information about the existing and the BLE proximity alert enabled preemption systems, the system components and interfaces between them, the planned capabilities, and the system architecture.